Chemical imaging explosives (CHIMED) optical sensor using SWIR

• US 8,368,880 B2
• Filed: 04/05/2010
• Issued: 02/05/2013
• Est. Priority Date: 12/23/2005
• Status: Active Grant

• Current Assignee: Chemimage Corporation
• Original Assignee: Chemimage Corporation
• Inventors: Treado, Patrick, Nelson, Matthew, Gardner, Charles W. Jr.
• Primary Examiner(s): Geisel, Kara E
• Application Number:
  US12/754,229
• Publication Number:
  US 20100225899A1
• Time in Patent Office: 1,037 Days
• Field of Search: 356 72- 73, 250/338.1, 250/339.11, 250/341.8
• US Class Current: 356/73
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 33/0057 for warfare agents or explosives properties of explosives G01N33/227

Abstract

A sample is illuminated to thereby generate a plurality of first interacted photons selected. The first interacted photons are assessed using a visible imaging device to thereby determine an area of interest in the sample. The area of interest is illuminated to thereby generate a plurality of second interacted photons. The second interacted photons are assessed using a spectroscopic device to thereby generate a SWIR data set representative of said area of interest. A database is searched wherein said database comprises a plurality of known SWIR data sets associated with an explosive material. The data sets comprise at least one of: a plurality of SWIR spectra and a plurality of spatially accurate wavelength resolved SWIR images. An explosive material in the area of interest is thereby identified as a result of the search.

Claims

1. A method comprising:

illuminating a sample to thereby generate a plurality of first interacted photons selected from the group consisting of;

photons absorbed by the sample, photons reflected by the sample, photons emitted by the sample, photons scattered by the sample, and combinations thereof;

assessing said plurality of first interacted photons using a visible imaging device, wherein said assessing comprises obtaining a visible data set representative of said sample;

analyzing said visible data set to thereby identify an area of interest in the sample;

illuminating said area of interest to thereby generate a plurality of second interacted photons selected from the group consisting of;

photons absorbed by the sample, photons reflected by the sample, photons emitted by the sample, photons scattered by the sample, and combinations thereof;

assessing said plurality of second interacted photons using a spectroscopic imaging device, wherein said assessing comprises obtaining a SWIR data set representative of said area of interest of said sample;

searching a SWIR database in accordance with the SWIR data set in order to identify a known SWIR data set from said SWIR database, wherein said SWIR database contains a plurality of known SWIR data sets, and wherein each known SWIR data set is associated with a known explosive compound; and

identifying an explosive compound in the area of interest based on the known SWIR data set identified by said searching.

2. The method of claim 1 further comprising passing at least one of said first plurality of photons and said second plurality of interacted photons through a multi-conjugate tunable filter.

3. The method of claim 1 further comprising passing at least one of said first plurality of interacted photons and said second plurality of interacted photons through a tunable filter selected from the group consisting of:

a Fabry Perot angle tuned filter, an acousto-optic tunable filter, a liquid crystal tunable filter, a Lyot filter, an Evans split element liquid crystal tunable filter, a Sole liquid crystal tunable filter, a fixed wavelength Fabry Perot tunable filter, an air-tuned Fabry Perot tunable filter, a mechanically-tuned Fabry Perot tunable filter, and a liquid crystal Fabry Perot tunable filter.

4. The method of claim 1 wherein said illuminating of at least one of said sample and said area of interest is performed at a standoff distance.

5. The method of claim 1 wherein said plurality of known SWIR data sets includes at least one of:

a plurality of SWIR spectra corresponding to the known explosive compounds and a plurality of spatially accurate wavelength resolved SWIR spectroscopic images corresponding to the known explosive compounds.

6. The method of claim 1 wherein said sample includes at least one of:

a human hand, a passport, a credit card, a driver'"'"'s license, a boarding pass, a human body part, a piece of human clothing, a human-wearable item, a shoe, an airline ticket, and combinations thereof.

7. The method of claim 1 wherein said known explosive compound is selected from the group consisting of:

nitrocellulose, nitroglycerin, 1,3,5-trinitroperhydro-1,3,5-triazine (“

RDX”

), 1,3,5,7-tetranitroperhydro-1,3,5,7-tetrazocine (“

HMX”

), 1,3-dinitrato-2,2-bis (nitratomethyl) propane (“

PETN”

), Ammonium Nitrate, and combinations thereof.

8. The method of claim 1 wherein said searching comprises applying a similarity metric that generates a score.

9. The method of claim 8 wherein said similarity metric is selected from the group consisting of:

a Euclidean distance metric, a spectral angle mapper metric, a spectral information divergence metric, a Mahalanobis distance metric, a spectral unmixing algorithm, principle component analysis, partial least squares regression, spectral mixture resolution, cosine correlation analysis, multivariate curve resolution, and combinations thereof.

10. The method of claim 1 wherein said analyzing of said visible data set further comprises searching a visible database in accordance with the visible data set in order to identify a known visible data set from said visible database, wherein said visible database contains a plurality of known visible data sets, and wherein each known visible data set is associated with one or more of the following:

an explosive compound, a formulation additive of an explosive material, a binder of an explosive material, a residue of an explosive material, and combinations thereof.

11. The method of claim 1 wherein said visible data set comprises a visible image representative of said sample.

12. The method of claim 1 wherein said visible data set comprises a RGB video image.

17. The method of claim 1 wherein at least one of said first plurality of interacted photons and said second plurality of interacted photons are collected using a telescope optic.

13. A method comprising:

illuminating a sample to thereby obtain a visible image representative of said sample;

determining whether a suspicious substance is present in said sample and a location of said substance in said sample based on said visible image of said sample, wherein said suspicious substance is selected from the group consisting of;

a chemical substance, a biological substance, a hazardous substance, and combinations thereof;

illuminating said location on said sample to thereby generate interacted photons selected form the group consisting of;

photons absorbed by the sample, photons reflected by the sample, photons emitted by the sample, photons scattered by the sample, and combinations thereof;

obtaining a SWIR signature of said suspicious substance based on said interacted photons; and

identifying said suspicious substance based on a comparison of said SWIR signature with a SWIR database containing a plurality of SWIR signatures associated with a corresponding plurality of known explosive materials.

14. The method of claim 13 wherein said visible image comprises a RGB video image.

15. A system comprising:

a visible imaging device for assessing a sample to indentify an area of interest;

an illumination source to illuminate at least one of the sample and an area of interest in the sample to thereby generate a plurality of first interacted photons selected from the group consisting of;

photons absorbed by the sample, photons reflected by the sample, photons emitted by the sample, photons scattered by the sample, and combinations thereof;

a tunable filter through which said interacted photons are passed, wherein said tunable filter is selected from the group consisting of;

a multi-conjugate tunable filter, a Fabry Perot angle tuned filter, an acousto-optic tunable filter, a liquid crystal tunable filter, a Lyot filter, an Evans split element liquid crystal tunable filter, a Sole liquid crystal tunable filter, a fixed wavelength Fabry Perot tunable filter, an air-tuned Fabry Perot tunable filter, a mechanically-tuned Fabry Perot tunable filter, and a liquid crystal Fabry Perot tunable filter;

a spectroscopic imaging device for assessing said interacted photons to thereby generate a SWIR data set representative of at least one of said sample and said area of interest in said sample; and

a SWIR database having plurality of known SWIR data sets, wherein each known SWIR data set is associated with one or more of the following;

a known explosive compound, a formulation additive of explosive material, a binder of explosive material, and combinations thereof.

16. The system of claim 15 wherein said visible imaging device comprises a RGB video camera.

18. The system of claim 15 further comprising a telescope optic for collecting said plurality of interacted photons.